1. Field of the Invention
The present invention relates to a system for monitoring low frequency sounds, and more specifically to a sound monitoring system for musicians that translates electrical signals corresponding to low-frequency sounds into mechanical energy, allowing the musician to sense the intensity and duration of those sounds by touch.
2. Description of the Prior Art
Much of modern music is performed utilizing electronic amplification, whether out of necessity given the electronic nature of the musical instruments themselves, or in response to the high sound volumes demanded by today's listeners. Unfortunately, under circumstances of high amplification, the volume of performance sound can interfere with and overwhelm the ability of the musicians to monitor their performances.
For example, most live band performances include a drummer. The drummer is traditionally positioned behind the other players, thereby allowing the drummer to hear a blend, or "mix" of the total performance sound in order to maintain consistency. However, under high sound volume conditions, the drummer usually requires a stage monitoring speaker independent from speakers designed to project sound to the audience, to provide a controlled sound reference for himself and for the other performers. The stage monitor speakers generally need to be large in order to reproduce the desired "mix" at very high sound pressure levels. Most often, the bass drum and bass guitar are the loudest components of this "mix", and the stage monitor speakers must reproduce the full sound of the instruments in order to assist the drummer to work along with the other members of the band.
The relatively high amplification required by the stage monitoring speaker creates two serious problems. First, longer sound waves generated by the low frequency component of the stage monitoring speakers permeate, or "bleed", into microphones that are transmitting the performance sound to the listeners. Unwanted mixing of monitoring sound and performance sounds can occur at different times, due to the varying distances between the microphones and the stage monitor speakers.
As a result of the unwanted transmission of low frequency sound waves from the stage monitor speakers into the microphones, the phase coherence of any given sound wave is unpredictably distorted. This distortion occurs because of the additive effect of combining slightly different phases of sound caused by the various distances between the microphones and the stage monitor. This interaction between monitoring and performance sound can compromise both the overall performance mix and the monitor mix.
Bleeding of low frequency sound waves from the stage monitor into the microphones also reduces control over the performance sound mix. The sheer sound pressure level from the stage monitor, in particular the lowest frequency sound waves which produce most of the energy, degrade the quality of sound produced by the individual instruments. For example, as an overhead microphone is brought up in volume to reproduce the cymbals, it will also capture sound of the entire mix of instruments generated by the stage monitor. When this interaction occurs, the individual sound quality of the respective instruments is lost, and the quality of the overall mix declines.
A second problem associated with conventional sound monitoring relates to the range of sound frequencies associated with the various instruments. For example, the low sound frequencies of the bass drum and bass guitar referenced by the drummer are in the frequency range of thirty-to-eighty cycles. At thirty cycles, the corresponding sound wave is almost forty feet long. As the drummer is typically about three feet from the stage monitor, the forty foot wave cannot properly develop to allow the drummer to hear it well.
Unfortunately, many musicians increase the volume of the stage monitor in order to compensate for this disparity between sound wavelength and distance from the stage monitor. Resulting elevated sound volume causes excessive consumption of power and abuse to the speakers, and often prompts the surrounding band members to play louder. The compounded increase in sound volume can damage the drummer's hearing. Hearing loss is today a common and serious problem among musicians.
While problems associated with conventional stage monitoring is described above with reference to the drums, these same problems also affect other instruments. For example, the bass guitar and keyboard often produce low frequency notes during a performance. Again, because performers want to "feel", as well as hear the sounds generated, bass players and keyboard players may seek to amplify their instruments beyond levels optimum for the performance "mix".
There have been a number of attempts to overcome problems associated with unwanted contamination of performance sound by monitoring sound. For example, many musicians now utilize in-ear monitors. While effective, in-ear monitoring systems are quite expensive. Other than the high cost, the biggest drawback associated with in-ear monitors is an ability to accurately reproduce adequate low frequencies due to the limitations in the size of earpiece diaphragms. Thus, performers who utilize in-ear monitors often find that they miss the "feel" of the core rhythm elements--the bass and kick.
Finally, it is important to note that problems associated with the mixture of performance and monitoring sound are not necessarily limited to the concert hall. In the recording studio, many musicians maintain their headphones at sufficiently high volume that enough sound escapes to be detected by open studio microphones. Again, this unwanted mixing of monitoring and performance sound can seriously degrade the quality of the music produced.
Accordingly, it is desirable to utilize a stage monitoring system that permits performers to detect and monitor low frequency sounds without having to resort to large stage monitor speakers.